JPH0592435A - Molding core and production thereof - Google Patents

Abstract

PURPOSE:To provide excellent moldability and water degradation properties by compounding hydroxy propyl cellulose with sand particles being a base material as a binder to knead the same with said particles and molding the resulting kneaded mixture into a required shape to dry the molded one. CONSTITUTION:Sand particles are prepared as a base material and hydroxy propyl cellulose is prepared as a binder. Next, the sand particles as the base material and hydroxypropyl cellulose as the binder are compounded and subsequently kneaded to obtain clayey paste. This clayey paste is pushed in a mold to be molded and the molded article is taken out of the mold to be dried to form a molding core 3. The molding core 3 is arranged to the molding space 2 of a master mold 1 and a resin such as a thermoplastic resin, a thermosetting resin or a reactive monomer is injected in the molding space 2 from a casting port under pressure to be cured or polymerized and the molded one is taken out of the master mold 1. The molding core 3 is degraded in water to easily produce a hollow car part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding core and a method for manufacturing the same.

[0002]

2. Description of the Related Art In the automobile industry, a technique for reducing the weight of a vehicle body is being developed for the purpose of improving fuel efficiency. Especially, in order to reduce the weight of the vehicle body, it is considered promising to use resin for various automobile parts.

When the automobile part to be made into resin is a hollow body, the resin is injected into a mold containing a core,
It is optimal to manufacture a hollow automobile part by taking out the core from the hollow part of the automobile part molded after resin cooling, but if the hollow automobile part has a complicated shape, Since it is difficult to remove the core, a sand core, a core made of a low melting point alloy, or the surface of the sand core is covered with a low melting point alloy to form a double structure core. For example, after cooling the resin, the sand core is disintegrated with water, or it is immersed in an oil bath at a temperature higher than the melting point of the low melting point alloy described above to make the core or double core of the low melting point alloy. It is considered to dissolve the core of the structure.

[0004]

However, the above-mentioned conventional molding core and its manufacturing method have the following problems.

That is, in the case of a sand core, it is difficult to manufacture a core which has all the requirements of having appropriate strength, excellent moldability and good water disintegration property. In the case of the core made of low melting point alloy, there is a problem that a large-scale device is required for manufacturing and immersing in the oil bath, and the cost type becomes high. There is a problem that the process is too complicated to be suitable for industrial production.

In view of the above circumstances, the present invention has an object to provide an inexpensive molding core having excellent moldability and water disintegration property, and a method for producing the same.

[0007]

The invention according to claim 1 relates to a molding core comprising sand particles as a base material and hydroxypropyl cellulose as a binder.

A second aspect of the present invention relates to a molding core comprising sand particles as a base material and hydroxypropyl cellulose and an alumina sol as a binder.

According to a third aspect of the present invention, sand particles as a base material are mixed with hydroxypropyl cellulose as a binder, kneaded, molded into a desired shape and dried to form a molding core. According to the present invention, there is provided a method for manufacturing a molding core.

According to a fourth aspect of the present invention, the sand particles as the base material are blended with hydroxypropyl cellulose and the alumina sol as the binder, kneaded, molded into a required shape and dried to form a molding core. The present invention relates to a method for producing a molding core, which is characterized in that

[0011]

According to the first and third aspects of the present invention, the sand particles as the base material are mixed with hydroxypropyl cellulose as the binder, and the mixture is kneaded, molded into a desired shape and dried. A molding core is manufactured by forming the child.

According to the second and fourth aspects of the present invention, the sand particles as the base material are mixed with hydroxypropyl cellulose and the alumina sol as the binder, kneaded, molded into a desired shape and dried, The molding core is manufactured by forming the molding core.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment of the present invention.

In FIG. 2, reference numeral 1 is a main mold such as a mold or sand mold having a molding space 2 inside, and 3 is a molding core arranged inside the molding space 2 of the main mold 1 with a gap. is there.

First, sand particles as a base material are prepared.

The sand particles are not particularly limited, but silica sand, alumina sand, zirconia sand and the like are preferable.

Similarly, hydroxypropyl cellulose as a binder is prepared.

The hydroxypropyl cellulose has a viscosity of 1 to 4000 CPS when made into a 2% aqueous solution,
It is preferably about 1 to 100 CPS, and an aqueous solution or a lower alcohol solution having a concentration of about 5 to 50 percent is used.

Next, hydroxypropyl cellulose as a binder is blended with the sand particles as the base material and kneaded.

The mixing ratio of the two varies depending on workability at the time of molding the core material to be obtained, drying strength, water disintegration property of the core, concentration of the binder to be mixed, and the like. As a rough guide, the binder solution is 8 to 15 g per 100 g of sand particles.

As a method of blending, a binder is added little by little to the sand particles and kneaded until a clay-like paste is formed.

Then, the clay-like paste produced as described above is pressed into a mold to be molded, and the molded body taken out of the mold is dried at, for example, 80 to 150 ° C. for about 30 minutes to 2 hours to form a molding core. 3 is formed.

The drying time can be shortened by using a lower alcohol such as methanol, ethanol or isopropanol as a binder solvent, or by adding a lower alcohol to an aqueous binder solution.

Molding core 3 manufactured in this way
Has excellent moldability and water disintegration, and can be manufactured at low cost.

Then, the molding core 3 is placed inside the molding space 2 of the main mold 1 as shown in FIG. 2, and a thermoplastic resin or a thermosetting resin is passed from a casting port (not shown) to the molding space 2. A hollow automobile part is easily manufactured by injecting a resin such as a reactive monomer under pressure, taking out from the main mold 1 after curing or polymerization of the resin, and disintegrating the molding core 3 with water.

FIG. 3 shows a second embodiment of the present invention.

The composition is the same as that of the above-described embodiment except that hydroxypropyl cellulose as an organic binder is mixed with alumina sol as an inorganic binder and then mixed with sand particles.

Here, the alumina sol is a colloidal solution containing 5 to 10% of boehmite-type alumina with water as a dispersant, and the mixing ratio of hydroxypropyl cellulose and alumina sol is such that the solid content of hydroxypropyl cellulose is The alumina content of the alumina sol is preferably about 1 to 10 with respect to 100.

The mixing ratio of the mixed aqueous solution of hydroxypropylcellulose and alumina sol to the sand particles is preferably about 8 to 15 g of the mixed aqueous solution per 100 g of the sand particles, and the mixed aqueous solution contains methanol, ethanol or isopropanol. The drying time can be shortened by adding a lower alcohol such as.

According to this embodiment, the same action and effect as those in the above-mentioned embodiment can be obtained, and in addition to the fact that a part of hydroxypropyl cellulose is transformed into a water-insoluble substance by the heat of the resin, it can be changed by the alumina sol. Since it can be reliably suppressed, better water disintegration can be obtained as compared with the above-mentioned examples.

FIG. 4 is a table showing the results of a comparative evaluation test for the water disintegration property of the molding core 3 of the present invention, in which various binder aqueous solutions were added little by little to 100 g of Enshu sand to obtain a clay-like paste. After kneading until it becomes, diameter 30mm and length 50
It is pressed into a pipe of mm to be molded, the molded body is extruded from the pipe, left at room temperature for 24 hours, and then dried at 120 ° C. for 1 hour to obtain a molding core 3, and the molding core 3 is cast with resin. It was heat-treated at 160 ° C. for 2 hours and then immersed in water at room temperature for 10 minutes for comparative evaluation of water disintegration.

In FIG. 4, PEO is an abbreviation for polyethylene oxide, PVA for polyvinyl alcohol, PVP for polyvinylpyrrolidone, PVPM for polyvinylpyrrolidone anhydrous maleate, HEC for hydroxyethyl cellulose, and HPC for hydroxypropyl cellulose. The addition amount is the amount per 100 g of Enshu sand. In addition, double circles are extremely good, circles are good, triangles are slightly good, and flutters are bad.

According to the above-mentioned evaluation test, it was confirmed that only hydroxypropyl cellulose had good drying property, heat resistance and water disintegration property.

The present invention is not limited to the above-mentioned embodiments, but can be used for manufacturing other than automobile parts, can be used for manufacturing other than hollow bodies made of resin material, and the like. Needless to say, various changes can be made without departing from the scope of the present invention.

[0036]

As described above, according to the molding core and the method for manufacturing the same of claims 1 to 4, the molding core has excellent moldability and water disintegration property and is inexpensive. The excellent effect of obtaining a core can be achieved.

[Brief description of drawings]

FIG. 1 is a process drawing for carrying out the method of the first embodiment of the present invention.

FIG. 2 is a perspective view of a main mold portion for manufacturing a hollow part using the molding core of FIG.

FIG. 3 is a process drawing for carrying out the method of the second embodiment of the present invention.

FIG. 4 is a table showing the results of a comparative evaluation test for the water disintegration property of the molding core of the present invention.

[Explanation of symbols]

 3 Core for molding

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Nobuyuki Hamano Inventor Nobuyuki Hamano 3-1, Hinodai, Hino City, Tokyo 1 Hino Motors Co., Ltd. (72) Inventor Yoichi Oba 3-1293-10 Higashiyamato, Tokyo Tateno Town 2-303, Ltd., Interface Technology Research Institute (72) Inventor, Yoshiyuki Shinno 2-3-3, Nihonbashi Horidomecho, Chuo-ku, Tokyo Kawaken Huain Chemical Co., Ltd.

Claims (4)

[Claims] 1. A molding core comprising a sand particle as a base material and hydroxypropyl cellulose as a binder. 2. A molding core comprising sand particles as a base material and hydroxypropylcellulose and an alumina sol as a binder. 3. A molding core is formed by blending sand particles as a base material with hydroxypropyl cellulose as a binder, kneading, molding into a required shape and drying. Manufacturing method of molding core. 4. A molding core is formed by blending sand particles as a base material with hydroxypropyl cellulose as a binder and alumina sol, kneading, molding into a required shape and drying. And a method for producing a molding core.